1. Field of the Invention
The invention refers to an apparatus for producing a coating on a laminar carrier member. The invention refers in particular to an apparatus for dressing leather, preferably split leather, or for dressing substrates being similar to split leather.
The term "substrate" is herein defined or comprising a tissue, a knitting or a fleece, which is manufactured from natural or synthetic fibres and which has, similar to split leather, at least on one side fibres protruding from the surface, i.e. has properties similar to that of split leather and can be used in place of split leather in the production of artificial leather. The split leather or substrate is, in such a case, provided with a thin coating formed of a thin foil and showing at its visible side the grain structure of natural leather, noting that the protruding fibres of the split leather or of the substrate become anchored within the foil forming the coating or, respectively, within the adhesive layer between the split leather or substrate, respectively, and the foil, so that there results an inseparable connection with this coating.
The foil forming the coating is produced by applying onto a supporting base comprising a surface consisting of silicone rubber or of silicone resin a liquid coating material which solidifies on the supporting base, which is preferably heated. The supporting base may consist of a plate member or of a belt, preferably of an endless circulated belt.
2. Description of the Prior Art
It is already known to improve the quality of the surface of split leather by applying thereon a film of synthetic plastics material. According to German Patent Specification No. 32 29 150, the procedure is, for example, such that a liquid coating material is applied onto a supporting base being provided with an embossed pattern having the appearance of the grain structure of natural leather and being heated to a temperature between 70.degree. and 185.degree. C. and is solidified there to a film showing the embossed pattern, onto which film is subsequently placed the split leather with interposition of an adhesive consisting, for example, of a polyurethane dispersion, noting that subsequently the split leather is compressed together with the film under the action of vacuum. The liquid coating material, which is applied onto the surface of the supporting base for forming the film, is, for example, an aqueous dispersion of synthetic plastics material, in particular a polyurethane dispersion. This procedure results in an excellent end product in which can be formed very thin foils as the dressing, noting that air inclusions within the dressing or between the dressing and the split leather are avoided and a visible surface of nice appearance can be obtained in spite of the different thickness at individual areas of the split leather.
Utilization of a supporting base of silicone rubber is particularly suitable in the production of the foil, because the surface of silicone rubber has a distinct mould releasing effect and anti-adhesive effect as well as strongly hydrophobic properties, so that the foil can easily be removed from the supporting base even if no mould release agent is used. It is in particular in case of a very thin foil, what is convenient for not impairing the desired leather-like properties by applying the foil, and in case of a supporting base showing on its surface a very fine embossed pattern resulting in a very fine grain on the visible side of the foil that there exists the risk that the solidified foil becomes removed in an undesired manner from the supporting base consisting of silicone rubber or is at least displaced on this supporting base, so that it becomes difficult or even impossible to apply thereon the split leather provided with the adhesive layer or folds are generated in the foil. It is in particular when forming the foil from a dispersion of synthetic plastics material that there exists a great risk that, on account of the hydrophobic properties of the silicone rubber, the foil is removed from the supporting base still prior to having contacted the split leather with the foil. Additionally it has to be considerated that for the purpose of rapidly solidifying the foil on the supporting base, blowers are used to heat this supporting base so that the solidified foil, particularly when it is very thin, is lifted off the base by the resultant draft.